Cold-Weather Power Station低温电力综合计算器
Three tabs: power-bank true capacity with cold derating, solar feasibility at winter camps, and headlamp runtime with cold batteries. 三个标签页：充电宝真实容量与低温衰减、冬季营地太阳能可行性、低温电池头灯续航。
How the winter power calculator works
Cold changes three things at once: usable battery capacity, the honesty of the mAh printed on a power bank, and the energy a small panel can actually harvest. This tool models each on its own tab using measured, datasheet-grade relationships rather than the marketing numbers on the packaging.
Cold derating and the warm-pocket trick
Lithium-ion usable capacity falls almost linearly with temperature: 100% at 25 °C, about 75% at 0 °C, 55% at −10 °C and 35% at −20 °C. The cells are not empty — their internal resistance rises and voltage sags under load, so the battery management system may shut down while a true 20–30% state of charge remains. Carrying the bank or phone in an inner jacket pocket or inside the sleeping bag is modelled as a +15 °C effective cell temperature, which recovers most of the loss. One rule has no workaround: never charge lithium cells below 0 °C. Charging a cold cell plates metallic lithium on the anode, causing permanent capacity loss and a genuine internal-short/fire risk later — warm the device above freezing first.
The “real mAh” of a power bank
Power-bank capacity is rated at the 3.7 V cell voltage, but phones charge from the 5 V USB output. Convert through energy and step-up efficiency: mAh5V = mAh × 3.7 ÷ 5 × efficiency. With a realistic 0.85 efficiency, a 10,000 mAh bank delivers only about 6,290 mAh at 5 V — 37 Wh, so it charges a 3,278 mAh phone roughly 1.9 times at room temperature, and less in the cold. The bank tab applies the cold coefficient on top of this and reports full phone charges for your exact trip temperature.
Solar and headlamps
Panel output is Wh ≈ watts × peak-sun hours × weather factor × 0.8 (heating, mismatch and thin USB cables). Southwest deserts see 5–6 peak-sun hours, the Pacific Northwest 3–4, but winter mountains only 1–2 — a 10 W panel can yield just 8–16 Wh on an average winter day. The lamp tab uses roughly 100 lm/W LED efficacy and AAA datasheet capacities: alkaline AAAs sag and fade early in cold while lithium AAAs (e.g. L92) keep their voltage far below freezing. SOS/red modes are modelled at a 30% duty cycle, and the plan always reserves the last 20% of light time for emergencies rather than counting it as working light.
计算原理
低温会同时改变三件事：电池可用容量、充电宝标称 mAh 的真实程度、以及小太阳能板的实际发电量。本工具分三个标签页，用符合数据表实测的关系建模，而不是包装上的营销数字。
低温衰减与贴身保温
锂离子电池的可用容量随温度近似线性下降：25 °C 为 100%，0 °C 约 75%，−10 °C 约 55%，−20 °C 约 35%。电量并没有消失——低温下内阻升高、带载时电压骤降，电池管理系统可能在真实剩余 20–30% 时就判定“没电”而关机。把充电宝或手机放在外套内侧口袋或睡袋里，等效于电芯温度 +15 °C，可挽回大部分损失。有一条规则没有变通：绝不在 0 °C 以下给锂电池充电。低温充电会让金属锂在负极析出，造成永久容量损失，并埋下内短路/起火隐患——先把设备焐到零度以上再充。
充电宝的“真实 mAh”
充电宝标称容量按电芯 3.7 V 计，而手机从 5 V USB 取电。按能量与升压效率换算：mAh5V = mAh × 3.7 ÷ 5 × 效率。取真实的 0.85 效率，10000 mAh 充电宝在 5 V 下只能输出约 6290 mAh（37 Wh），在室温给 3278 mAh 的手机只能充约 1.9 次，低温下更少。充电宝标签页在此基础上再叠加低温系数，按你的实际气温计算手机充电次数。
太阳能与头灯
太阳能板发电量为 Wh ≈ 功率 × 峰值日照小时 × 天气系数 × 0.8（综合发热、失配与细 USB 线损耗）。美国西南沙漠峰值日照 5–6 小时，太平洋西北 3–4 小时，而冬季山地只有 1–2 小时——10 W 小面板在冬季普通一天可能只发 8–16 Wh。头灯标签页按 LED 约 100 lm/W 光效与 AAA 数据表容量计算：碱性 AAA 在寒冷中会早早压降衰竭，而锂铁 AAA（如 L92）在远低于冰点时仍能维持电压；SOS/红光按 30% 占空比建模，并且始终预留最后 20% 续航作为应急，不计入工作照明。